Pack carburising

The earliest method of case hardening, in which components were packed into a suitable box, together with carbon-bearing materials such as charcoal, hooves, hide, animal fat and horn, and heated to the carburising temperature.

Modern pack carburising is normally carried out using a less-variable carburising agent, such as charcoal, and an energiser, such as barium carbonate.

Pack carburising is very inefficient in that close control of the case depth and quality is difficult and quenching from the carburising temperature is not possible. It is really only good for one-off components, where controlled industrial processes are not available or are too expensive.

Occasionally called box carburising.